hal_intr.c

来自「eCos操作系统源码」· C语言 代码 · 共 107 行

//==========================================================================
//
//      hal_intr.c
//
//      PowerPC interrupt handlers
//
//==========================================================================
//####ECOSGPLCOPYRIGHTBEGIN####
// -------------------------------------------
// This file is part of eCos, the Embedded Configurable Operating System.
// Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
// Copyright (C) 2003 Gary Thomas
//
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// the terms of the GNU General Public License as published by the Free
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// WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
// for more details.
//
// You should have received a copy of the GNU General Public License along
// with eCos; if not, write to the Free Software Foundation, Inc.,
// 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
//
// As a special exception, if other files instantiate templates or use macros
// or inline functions from this file, or you compile this file and link it
// with other works to produce a work based on this file, this file does not
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// this file might be covered by the GNU General Public License.
//
// Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.
// at http://sources.redhat.com/ecos/ecos-license/
// -------------------------------------------
//####ECOSGPLCOPYRIGHTEND####
//==========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):    jskov
// Contributors: jskov
// Date:         1999-02-20
// Purpose:      PowerPC interrupt handlers
// Description:  This file contains code to handle interrupt related issues
//               on the PowerPC.
//
//####DESCRIPTIONEND####
//
//==========================================================================

#include <pkgconf/hal.h>

#include <cyg/hal/hal_intr.h>

static unsigned long ticks_per_us;

externC void
hal_IRQ_init(void)
{
    // No architecture general initialization, but the variant may have
    // provided some.
    hal_variant_IRQ_init();

    // Initialize real-time clock (for delays, etc, even if kernel doesn't use it)
    HAL_CLOCK_INITIALIZE(CYGNUM_HAL_RTC_PERIOD);

    // Pre-calculate this factor to avoid the extra calculations on each delay
    ticks_per_us = ((long long)1 * (CYGNUM_HAL_RTC_PERIOD * 100)) / 1000000;
}

// Delay for some number of useconds.
externC void 
hal_delay_us(int us)
{
    cyg_int32 old_dec, new_dec;
    long ticks;
    int diff;

    // Note: the system constant CYGNUM_HAL_RTC_PERIOD corresponds to 10,000us
    // Scale the desired number of microseconds to be a number of decrementer ticks
    if (ticks_per_us > 0) {
        ticks = us * ticks_per_us;
    } else {
        ticks = ((long long)us * (CYGNUM_HAL_RTC_PERIOD * 100)) / 1000000;
    }
    asm volatile("mfdec  %0;" : "=r"(old_dec) : );
    while (ticks > 0) {
        do {
            asm volatile("mfdec  %0;" : "=r"(new_dec) : );        
        } while (old_dec == new_dec);
        if (new_dec < 0) {
            HAL_CLOCK_RESET(0, CYGNUM_HAL_RTC_PERIOD);
        }
        diff = (old_dec - new_dec);
        if (diff < 1) diff = 1;
        old_dec = new_dec;
        ticks -= diff;
    }
}

// -------------------------------------------------------------------------
// EOF hal_intr.c